The present invention is a modification of the femoral compression devices disclosed in the patents U.S. Pat. No. 5,307,811 and EP 0 462 088 B1, which are assigned to the present assignee and which claim priority from SE 9002077 and SE 9003271. A femoral compression device according to these publications comprises basically a pressurizing means for compressive bearing against a puncture site at a femoral artery of a patient, a belt adapted to be fixed around the patient's body, and a base plate supporting the pressurizing means and being provided with two extensions. The pressurizing means according to these publications is a pneumatic device in the form of an inflatable air cushion or balloon, different embodiments of which have also been disclosed in U.S. Pat. No. 5,542,427, WO 94/05221, WO 98/34547 and U.S. application Ser. Nos. 09/355,736, 10/209,974 and 10/235,859, which all are assigned to the present assignee. All of the documents cited in this paragraph are incorporated herein by reference.
In use, the inflatable air cushion is positioned over a femoral artery of a patient, and the belt, which extends from the end of the first extension, around the patient's body and to the end of the second extension, is tightened. Then, the inflatable air cushion is inflated by a hand pump to a certain internal pressure, thereby expanding the air cushion such that the femoral artery is compressed in order to prevent bleeding through a puncture hole being made in the artery wall. The internal pressure, which can be read from a pressure gauge provided on the pump, should be raised to a value between the diastolic pressure and the systolic pressure—which is a procedure that has proven to work very well for the vast majority of patients.
An inherent characteristic of a pneumatic device, and in particular of the inflatable air cushion described above, is that the internal pressure only within a certain operating range corresponds to an increased length of stroke (i.e. increased expansion of the air cushion). For a pressurizing means in the form of an inflatable air cushion, this feature implies that when the air cushion has reached its maximal expansion, a further increase of the internal pressure does not expand the air cushion any more, which, in turn, means that no more compression pressure can be applied on the femoral artery. Normally, i.e. for the vast majority of patients having a normal or ordinary body constitution, this is of no problem since the length of stroke (i.e. the expansion) of the air cushion corresponds to the expansion needed to completely, or almost completely, compress the artery such that the flow of blood therethrough is significantly reduced, to thereby prevent bleeding from the puncture wound. In other words, the operating range of the air cushion ranges from a minimum value where the flow of blood is essentially unrestricted to a maximum value where the flow of blood is essentially completely stopped.
However, for those patients where the femoral artery is embedded in a very thick layer of adipose tissue, it can be difficult to determine whether the air cushion has reached its maximal expanded state, in which no more compression of the femoral artery is possible. And when a pressure gauge is used, this problem is even more pronounced because the pressure gauge continues to show increasing values even though the air cushion has reached its maximal expansion. This behaviour may give an inexperienced user a deceitful impression that the compression pressure on the femoral artery actually is increasing. Needless to say, such a misjudgement may give rise to very serious complications.
Another disadvantage with an inflatable air cushion is that if the patient moves, e.g. bends forward, after the femoral compression device has been positioned around the patient's body, the compression pressure on the femoral artery is drastically reduced, because an air cushion, which only contains a small volume of air, has essentially no internal resilience. In other words, if there is a difference in the distance between the base plate and the femoral artery for the two different postures of the patient, the air cushion cannot compensate for this difference, which implies that there is essentially no compression pressure applied for the posture involving the longer distance between the base plate and the femoral artery.